WO2009068041A1 - Structure optique tridimensionnelle - Google Patents

Structure optique tridimensionnelle Download PDF

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Publication number
WO2009068041A1
WO2009068041A1 PCT/DK2008/050281 DK2008050281W WO2009068041A1 WO 2009068041 A1 WO2009068041 A1 WO 2009068041A1 DK 2008050281 W DK2008050281 W DK 2008050281W WO 2009068041 A1 WO2009068041 A1 WO 2009068041A1
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Prior art keywords
layers
optical structure
structure according
radiation
target analyte
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Jörg HÜBNER
Lars Pleth Nielsen
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Danish Technological Institute
Danmarks Tekniske Universitet
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Danish Technological Institute
Danmarks Tekniske Universitet
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65—Raman scattering
    • G01N21/658—Raman scattering enhancement Raman, e.g. surface plasmons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals

Definitions

  • the present invention relates to an optical structure suitable for surface-enhanced spectroscopy based on a three-dimensional nanostructure.
  • the invention also relates to an optical system, particularly suitable for high sensitivity detection, and a corresponding method for detection of a target analyte with surface- enhanced spectroscopy based on surface plasmons (SP), e.g. Surface-Enhanced Raman Scattering (SERS).
  • SP surface plasmons
  • SERS Surface-Enhanced Raman Scattering
  • Raman scattering is a unique technique for identification of molecular species since the re-emitted Raman photons correspond to a transition between a particular set of vibrational modes. Hence, by measuring the frequency of the emitted Raman photons it is in principle possible to identify the molecule causing the emission. Furthermore, the concentration of the specific molecule can by quantified by counting the number of photons with that specific frequency combined with a proper calibration. Unfortunately, the cross section for the
  • Raman process is very small and only about one out of every 10 12 incident photon will undergo Raman scattering. Due to this very low cross section it has so far only been possible to apply Raman spectroscopy in situations where there is a large concentration and/or numbers of molecules to be analyzed.
  • US 2006/0197953 discloses a metallic nanoparticle-coated thermoplastic film and the process for preparing such a film.
  • the plasmon resonance absorption spectrum of the film may be shifted by stretching or shrinking the coated film, i.e., the position of the absorption may be varied by mechanically influencing the coated film, cf. figures 2-4 for illustration of the effect.
  • the optical structure can be multilayered and transparent to obtain an accumulated effect of the absorption. This can be used for instance in connection with a sensor or similar devices.
  • the relevance or application for inelastic scattered light, e.g. SERS or the like, is however not disclosed.
  • the present invention is not related to frequency shift or tunability as suggested by US 2006/0197953.
  • SERS surface plasmon resonance
  • US 2006017918 provide an optical structure with dual- and/or multi-layer metal film-over-nanostructure (FON) substrates.
  • Dual-FON and Multi-FON SERS substrates comprise a rough nano-structured layer and two or more SERS-active metal film layers deposited thereon with a layer of dielectric material between the metal film layers.
  • SERS substrates there is provided a way of increasing the intensity of a Raman signal during surface-enhanced Raman spectroscopy using the SERS substrates.
  • the optical structure is not stable because the surface of the optical structure degrades over time, cf. figure 4 of US2006017918.
  • this optical structure has a relatively small effective surface area.
  • This substrate also suffers from an inherently random structure and there are problems with reproducibility due to the demonstrated deterioration of the surface.
  • an improved optical structure would be advantageous, and in particular a more efficient and/or reliable optical structure would be advantageous.
  • the invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-mentioned disadvantages singly or in any combination.
  • SP surface enhanced spectroscopy based on surface plasmons
  • the layers being at least partly transparent to radiation (R_in, R_out) for use in spectroscopy based on surface plasmons (SP), wherein the plurality of layers is optically arranged with respect to a surface of the optical structure so as to facilitate multiple surface plasmon (SP) enhancement due to inelastic scattering of radiation (R_in) entering the said surface, and wherein the plurality of layers is arranged so as to allow direct access for a target analyte (T) into and/or onto the plurality of layers.
  • SP surface plasmon
  • the invention is particularly, but not exclusively, advantageous for obtaining an optical structure wherein the surface plasmon (SP) based optical sensitivity may be increased by essentially going from a two-dimensional (2D) optical structure, as known in prior art, to a three-dimensional (3D) optical structure. If a 2D optical structure enables a sensitivity factor of 10 12 , preliminary tests and calculations indicate that sensitivity factors as high as 10 18 may be reached. Furthermore, the sensitivity is expected to be even higher since the present invention enables an optical structure where the target analyte may be distributed on the plurality of layers with SP-active sites, i.e. there may be a build-up in concentration due to the layers functioning as a filtration mechanism.
  • 2D optical structure enables a sensitivity factor of 10 12
  • preliminary tests and calculations indicate that sensitivity factors as high as 10 18 may be reached.
  • the sensitivity is expected to be even higher since the present invention enables an optical structure where the target analyte may be distributed on the plurality of layers with SP-active sites,
  • the term "partly transparent” means that, within a relevant optical region, e.g. ultraviolet (UV), visible (VIS), or infrared (IR), there is a transmission of at least 15%, preferably at least 30%, or more preferably at least 70%. In some embodiment, the transparency may be up to 90% or almost 100%, if the material of the layers is almost completely transparent in the relevant optical interval of wavelengths.
  • a relevant optical region e.g. ultraviolet (UV), visible (VIS), or infrared (IR)
  • the plurality of layers may be periodically arranged in a direction (A) towards the surface of the optical structure.
  • Advantageous optical effects e.g. resonances, may be obtained from this periodicity.
  • the periodicity may have several periods.
  • the direction (A) may be substantially orthogonal to the surface of the optical structure so as to provide a simplified geometry of the optical structure itself and/or of the optical system where the optical structure is a component or a part, e.g. as a sensing or enhancing unit, or as a filter unit.
  • the said orthogonality of the direction (A) may be globally for the entire optical structure, or alternatively the said orthogonality of the direction (A) may be locally, possibly several different orthogonal directions may be defined if for instance the optical structure has a non-plane surface, e.g. a curved surface.
  • the SP-active sites on the plurality of layers may be additionally prepared with dedicated bonding sites suitable for bonding a desired target analyte (T) for spectroscopy based on SP in the optical structure.
  • These sites may include, but are not limited to, mechanical roughening, chemical ligands, biochemical probe- molecules, etc.
  • the biochemical bonding sites may provide bonding that may be taken to include any kind of interaction between corresponding pairs of molecules that exhibit mutual affinity or binding capacity, typically specific or non-specific binding or interaction.
  • the SP-active sites may be metallic nanoparticles, where the term "metallic” means elemental metal or compounds thereof.
  • the term “nanoparticles” means particles with an average diameter of 5, 10, 15, 20, 25, 30, etc. up to 50 or 100 nm.
  • one or more layers of the plurality of layers is a thin metal layer in combination with metallic nanoparticles.
  • the thin metal layer should be sufficiently thin so as so allow at least some radiation to penetrate the layer.
  • the SP-active sites on one or more layers may be arranged in an ordered array of sites. Some arrays structure may be quadratic web, where the particles are arranged in square-like relation to each other or other similar geometric shapes.
  • the plurality of layers may have a porous structure for enhanced bonding of a target analyte (T) in the optical structure.
  • the layers may effectively function as a filter; preferably with dedicated adsorption sites.
  • Each layer may be described as a porous membrane with penetrating holes for the target analyte (T).
  • the plurality of layers may be interconnected and curved to form a roll. This will be termed a so-called “nano-roll”; where the plurality of layers is connected so as to form a single layer. This may performed via stress- induced rolling or by rolling of a sufficiently flexible material, e.g. a polymer. This will be further explained in detail below.
  • the layers may be substantially plane layers, the layers being arranged substantially parallel to each other. Possibly, this parallel arrangement is global for the optical structure, or alternatively limited to a local portion of the optical structure. Possibly, distances between layers may be comparable, preferably substantially equal, to an average diameter of the metallic nanoparticles on the different layers. The comparable size of particles and layer distance may be exploited in connection with resonances. Alternatively or additionally, distances between the nanoparticles in the array on a layer are comparable, preferably substantially equal, to an average distance to the two neighboring layers. Furthermore, distances of arrayed particles may be comparable, preferable substantially equal to a multiple of half the wavelength of the radiation (R_in) entering the surface, when said radiation is a substantially monochromatic radiation, e.g. a laser source.
  • R_in wavelength of the radiation
  • the distances between layers may be below a distance chosen from the group of: 5, 10, 15, 20, 25, 30, 35, 40, or 50 nanometers. It is expected that layer distances is short due to fast decay of the SP-light coupling, i.e. related with the distance in powers of 3 or 6.
  • the optical structure may comprise a fluid channel arranged for conveying a fluid with a possible target analyte (T) past and/or through the plurality of layers for deposit of the target analyte on the SP- active sites.
  • the fluid may be a gas or a liquid.
  • the optical structure may be integrated together with the fluid channel so as to form a probe, preferably for on-site testing. More preferably, the probe may be a disposable probe.
  • the fluid channel may comprise a portion oriented along the plurality of layers. In another embodiment, the fluid channel may comprise a portion oriented substantially perpendicular to the plurality of layers, when the plurality of layers are substantially parallel to each other.
  • the SP-active sites may comprise Au, Ag, Al, Na, Pt, or Cu. Alloys thereof and mixture/composites of these metals may also be applied.
  • the layers may comprise poly-crystalline Si, single-crystalline Si, SiO 2 , Si 3 N 4 , Al, AI 2 O 3 , TiO 2 , SiON-compounds, or glass (Phosphor- and/or Boron-doped), or doped variations of these materials.
  • the layers may comprise polymers, preferably porous polymers. It may be doped polymer or co-polymers. In one variant, the polymer may have embedded SP active sites.
  • the present invention relates to an optical system for detection of a target analyte (T) with surface enhanced spectroscopy based on surface plasmons (SP), the system comprising:
  • optical structure according to the first aspect, wherein the optical structure is optically connected to:
  • R_in radiation suitable for spectroscopy based on surface plasmons (SP) so as to detect the target analyte (T), and/or
  • R_out emitted radiation
  • the optical structure and/or the radiation unit and/or the detector unit may be arranged for performing the following kind of spectroscopy: Raman, surface-enhanced Raman spectroscopy (SERS), surface-enhanced resonance Raman spectroscopy (SERRS), second harmonic generation (SGH), hyper Raman, or coherent anti-Stokes Raman scattering (CARS).
  • SERS surface-enhanced Raman spectroscopy
  • SERRS surface-enhanced resonance Raman spectroscopy
  • SGH surface-enhanced resonance Raman spectroscopy
  • CDARS coherent anti-Stokes Raman scattering
  • the present invention relates to a method for detection a target analyte (T) with surface-enhanced spectroscopy based on surface plasmons (SP), the method comprising: - emitting radiation (R_in) on an optical structure according to the first aspect, the radiation being suitable for surface enhanced spectroscopy based on surface plasmons (SP), and
  • FIG. 1 schematically shows an optical system according to the present invention
  • FIG. 2 schematically shows a plurality of surface plasmon (SP) active layers according to the present invention
  • Figure 3 is a schematic cross-sectional view of an optical structure according to the present invention.
  • Figures 4 and 5 are schematic cross-sectional views of two different embodiments of an optical structure according to the present invention
  • Figure 6 schematically shows an a cross-sectional view of optical structure having a fluid of target analyte flowing through according to the present invention
  • Figure 7 is a step-by-step schematic description of how to construct a so-called hanging membrane embodiment according to the present invention
  • Figure 8 is a stacked configuration of the hanging membrane embodiment according to the present invention.
  • Figure 9 is a step-by-step schematic description of how to construct a so-called nano-roll embodiment according to the present invention.
  • Figure 1 schematically shows an optical system according to the present invention for detection a target analyte T with surface-enhanced spectroscopy based on surface plasmons (SP).
  • the target analyte T may be in a fluid, i.e. a gas or a liquid of any kind or type.
  • the system has a radiation unit 20 capable of emitting radiation R_in suitable for spectroscopy based on surface plasmons (SP) so as to detect the target analyte (T).
  • the radiation unit 20 may be arranged for performing the following kind of spectroscopy: Raman, surface enhanced Raman spectroscopy (SERS), surface enhanced resonance Raman spectroscopy (SERRS), second harmonic generation (SGH), hyper Raman, or coherent anti-Stokes Raman scattering (CARS).
  • the system also has an optical structure 10 for surface-enhanced spectroscopy based on surface plasmons SP.
  • the structure comprises a plurality of layers 11a, lib, and lie, the layers having SP-active sites 12, cf. Figure 2.
  • the layers are at least partly transparent to radiation R_in and R_out for use in spectroscopy based on surface plasmons (SP).
  • the plurality of layers 11a, lib, and lie are optically arranged with respect to a surface 13 of the optical structure 10 so as to facilitate multiple surface plasmon (SP) enhancement due to inelastic scattering of radiation entering the said surface 13.
  • the plurality of layers 11a, lib, and lie are arranged so as to allow direct access for a target analyte T into and/or onto the plurality of layers. This is schematically indicated with the entry 15 in the optical structure 10. This can however be obtained in a variety of different ways as it will be readily appreciated.
  • the optical structure 10 is optically connected to the radiation unit 20, and a detector unit 30 arranged for detecting emitted radiation R_out from the optical structure 10 so as to detect the presence and/or the concentration of the target analyte T on and/or within the layers 11a, lib, and lie.
  • a detector unit 30 arranged for detecting emitted radiation R_out from the optical structure 10 so as to detect the presence and/or the concentration of the target analyte T on and/or within the layers 11a, lib, and lie.
  • any number of layers can be applied within the context of the present invention on the condition that the incoming radiation R_in can penetrate trough a number of layers (not necessarily all the layers 11), and correspondingly that the emitted radiation R_out can penetrate out of the optical structure 10 to facilitate detection of the outgoing radiation R_out.
  • the incoming radiation R_in will typically have a spectrum dominated by a single frequency f_0 with a certain intensity, for example emitted by a laser.
  • the majority of the radiation R_in will typically be elastic scattered (no change of energy), and correspondingly there will be a relatively large peak in the spectrum of the outgoing radiation R_out at the same frequency; f_0.
  • due to the inelastic scattered radiation there will also be a much smaller but significant peak in the spectrum at another frequency: f_l.
  • the inelastic scattered radiation is conventionally called Stokes lines, and for f_l > f_0, the inelastic scattered radiation is conventionally called anti-Stokes lines.
  • the inelastic scattered radiation is generally orders of magnitude lower than the elastic scattered radiation, which therefore requires dedicated and highly sensitive detections means.
  • the number of layers 11 in the plurality can be at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. Alternatively, the number of layers 11 in the plurality can be at least 30, 40, 50, 60, 70, 80, 90 or 100.
  • the detector unit 30 may, in one embodiment, be integrated with the radiation unit 20.
  • FIG. 2 schematically shows a plurality of surface plasmon (SP) active layers 11 forming part of the optical structure 10 for surface enhanced spectroscopy based on surface plasmons SP.
  • the structure comprises a plurality of layers 11 with surface plasmon (SP) active sites 12, i.e. the SP-active sites 12 may comprise Au, Ag, Al, Na, Pt, or Cu, or alloys thereof, or mixture/composites thereof.
  • SP surface plasmon
  • the layers 11 are at least partly transparent to radiation R_in and R_out for use in spectroscopy based on surface plasmons (SP), i.e. the layers 11 may comprise poly-crystalline Si, single-crystalline Si, SiO 2 , Si 3 N 4 , Al, AI 2 O 3 7 TiO 2 , SiON- compounds, or glass (phosphor and/or Boron doped), or doped variations of these materials.
  • the layers may comprise polymers, preferably porous polymers. It should be mentioned that SU8 can advantageously be applied, but any doped polymer or co-polymers may be applied.
  • the polymer can have embedded SP active sites in order to ease manufacturing.
  • the substrate material may be a structured or pre-patterned thin film structured in such a way that the refractive index becomes negative.
  • the layers 11 can be stacked, i.e. arranged substantially parallel to each other with respect to a normal direction A. More particularly, the layers 11 can be periodically arranged with a distance D. The layers 11 may also be periodically arranged with several inter-layer distances, i.e. Dl, D2, D3, Dl, D2, D3 etc.
  • the SP-active sites 12 on the plurality of layers 11 can be prepared with dedicated bonding sites suitable for bonding a desired target analyte (T) for spectroscopy based on surface plasmon (SP) in the optical structure 10.
  • Such bonding sites can include, but are not limited to mechanical roughening, appropriate chemical ligands (preferably surface bonded), biochemical probe-molecules (specific or non-specific), etc., near or on the sites.
  • Figure 3 is a schematic cross-sectional view of an optical structure 10 similar to Figure 2, where the plurality of layers 11 is periodically arranged in a direction A towards the surface 13 of the optical structure 10.
  • the distance between the layers 11 can be approximately distance D, possibly several distances, Dl, D2, D3, etc.
  • the direction A may be substantially orthogonal to the surface 13 of the optical structure 10. If the surface 13 is rough, the direction A may be approximately orthogonal to an average surface plane of the surface 13.
  • Figures 4 and 5 are schematic cross-sectional views of two different embodiments of an optical structure 10 corresponding to Figure 3.
  • the embodiment of Figure 4 differs in that the layers 11 are periodically arranged with respect to a direction A which is not orthogonal to the surface 13, but rather has a certain angle different from 90 degrees with respect to the surface 13.
  • the embodiment of Figure 5 differs in that the layers 11 are randomly oriented with respect to each other, and with respect to the surface 13. This may, for example, be the case when the manufacturing of the layers 11 in the optical structure 10 is not completely controllable, e.g. if the layers are grown as self- assembled layers, by electrochemical deposition, etc. As will be explained in more detail below in connection with Figure 9, it is also possible that the optical structure 10 may be provided by mechanical bending of microscopic structures.
  • Figure 6 schematically shows a cross-sectional view of optical structure 10 having a fluid of target analyte T flowing through from entry 15a to exit 15b.
  • the optical structure 10 may inherently comprise a fluid channel arranged for conveying a fluid with a possible target analyte T past and/or through the plurality of layers 11 for deposit of the target analyte on the surface plasmon (SP) active sites.
  • the optical structure 10 can be integrated together with the fluid channel so as to form a probe, preferably for on-site testing. Due to the significantly increased sensitivity of the surface-enhanced spectroscopy provided by the present invention, such an optical detection system may provide increased safety and reliability in for example security application for monitoring chemical and/or biological hazardous material.
  • the fluid channel may convey gas (of any pressure, in particular also low pressure gas e.g. near vacuum conditions) or liquid.
  • FIG. 7 is a step-by-step schematic description of how to construct a so-called hanging membrane embodiment according to the present invention.
  • an optical structure 100a for surface-enhanced spectroscopy based on surface plasmons (SP) comprises a fluid channel 500 formed in a substrate, and a porous layer with SP active sites, the layer being arranged so as to substantially close the fluid channel 500 from above.
  • the porous layer functions as a filter during fluid conduction through the channel 500.
  • the hanging SP active membrane has the capability to combine e.g. the known Raman gain associated with thin metal films, nano-particles, colloidal particles etc. with the ability to filtrate air or liquid in an ongoing flow. This will allow for an up concentration of the molecular species to be identified by there associated RAMAN fingerprints increasing the sensitivity of the sensor unit even further.
  • This filtration effect and the SP enhancing effect may be combined in an optical structure formed by an ordered array of holes in a hanging Au membrane with build in flow channel(s).
  • the SP active material (ex. Au, Ag, Pt, Al, and Na etc.) may be deposited on a hanging membrane constructed from a suitable material (ex. polymer, Si3N 4 , SiO 2 , AI2O3, TiO 2 etc.).
  • the air or the liquid fluid may be transported through the hanging membrane by a build in flow channel(s) formed by under-etching the hanging membrane.
  • the substrate material may be a structured or pre-patterned thin film structured in such a way that the refractive index becomes negative.
  • the hanging membrane may be manufactured by conventional wafer process technologies as schematically indicated in Figure 7. A vast variety of alternative manufacturing processes are of course available to the skilled person within the context of the present invention. Below, each of the steps A-F is briefly described: Step A: Standard lithography is applied to define the structure of the hanging SERS active membrane on a substrate 110 applying conventional resist 200. The structuring of the membrane (Step A) may involve the use of self assembled nano/micro particles to structure the array of holes in the membrane.
  • Step B The SP-active metal layer 300 is deposited by e-beam, sputtering or alternatively by electrochemical deposition.
  • Step C The resist is dissolved whereby the overlying metal is removed.
  • Step D A second resist mask is added 400 defining the area where the membrane is to be under-etched during step E.
  • Step E Etching.
  • Step F The second mask is removed.
  • the etching depends critically on the used substrate 110. In case this is formed by SiO 2 , it is possible to perform the under etch by a solution of hydrofluoric acid (HF). In case the substrate is Si it is possible to form the under- etch by Potassium hydroxide solution (KOH). Alternatively, designed plasma etches can be driven into regimes where they also can perform isotropic etches capable of making a free hanging membrane. In the case where the substrate is polymer, a plasma-containing oxygen can be optimized to create hanging membranes.
  • HF hydrofluoric acid
  • KOH Potassium hydroxide solution
  • the optical structure 100a may have one or more photonic band gaps (PBG) known to be associated with periodic air holes in high index waveguides.
  • PBG photonic band gaps
  • These waveguides could be made of e.g. Si3l ⁇ l 4 , SiON or other high index materials.
  • the SP active metal can either be added before or after the holes have been created in the membrane.
  • the SP active membrane may also be formed without an underlying support, i.e. as a free hanging metal membrane full of holes.
  • the holes may have a random periodicity or alternatively they may form a well-ordered array. Instead of holes it would also be possible to add protrusions or SP active nano/micro particles onto a hanging membrane.
  • FIG. 8 is a stacked configuration of the hanging membrane embodiment according to the present invention.
  • the optical structure based on a single hanging membrane 100a will be two-dimensional although the evanescent field will penetrate a few micrometers to each side of the SP active membrane.
  • a three-dimensional optical structure 100 can be developed by adding 2 or more layers 100b of hanging SP active membranes onto the single layer configuration 100a.
  • the SP enhancement factor of this optical unit composed of n membranes is expected to be at least n times more sensitive, particularly for SERS activity.
  • the hole in the membrane of the structure 100a may be very tiny (200-300 nm) and may be fabricated by lithographic techniques or by self-assembled monolayer technology (SAM), which has shown to be a feasible production technology for large scale production of nano structures beyond the limits of conventional contact lithography.
  • SAM self-assembled monolayer technology
  • the nano holes in the membrane will be combined with flow of air or a liquid through the holes enabling a combined particle filtration built into the optical structure 100.
  • the holes will function as both SP spectroscopy gain centers, e.g. for Raman, forming "hot spots", and at the same time the holes will simultaneously function as a filtration unit causing an up concentration of particles in close proximity of the SP active membrane. This will increase the sensitivity of the SP detector/flow unit beyond that known previously from the literature in this field.
  • the concepts can be developed into two or more stacked membranes 100b as indicated in Figure 8 in order to increase the gain even further.
  • Figure 9 is a step-by-step schematic description of how to construct a so-called nano-roll embodiment of an optical structure 150. It should be noted how the plurality of layers 11 in the final roll (lower part of Figure 9) is arranged so as to facilitate multiple SP enhancement and that a target analyte (not shown) may access the plurality of layers. Also, the layers 11 may be periodically arranged with respect to a direction A.
  • the optical structure 150 will now be explained with reference to a SERS embodiment, but this nano-roll embodiment may also be applied for other kinds of surface plasmon (SP) based spectroscopy.
  • SP surface plasmon
  • the optical structure 150 may be formed from a substrate 120 onto which is added a SERS active material 200.
  • the bilayer structure is subsequently exposed to an anodic etch in an electrolyte by adding a positive bias voltage to the substrate and the negative pole to a working electrode of e.g. Pt.
  • a working electrode of e.g. Pt e.g. Pt
  • the substrate 120 is oxidized into material 300 and at the same time the process is forming and array of more or less well-ordered holes.
  • the stress introduced by the anodic etch will cause the bilayer structure to curl into a nano-roll forming a cylindrical three-dimensional optical structure 150 suitable for SERS. It may be necessary to add spacers 400 in order to form open flow pathways into the optical structure 150.
  • SERS active material e.g. Au
  • Al deposition with conventional lift-off and/or self-assembled monolayer (SAM)
  • SAM self-assembled monolayer
  • ⁇ 4 ⁇ lO 3 MPa
  • the anodic etch of Al into AI2O3 may also be substituted by other materials and combinations hereof.
  • Alternative candidates may be Si or Ti which can be converted into SiC>2 and TiC>2.
  • the nano-roll it may be formed on a substrate material that might be structured or pre-patterned in such a way that the refractive index becomes negative.
  • the invention relates in a further aspect 5 to an optical structure comprising a metal part structured in such a way that a negative index of refraction (N) is obtained at optical frequencies, the structure comprising :
  • the layers having a metal part structured in such a way that a negative index of refraction (N) is obtained at optical frequencies
  • the plurality of layers 11 is arranged so as to allow direct access for a target analyte (T) into and/or onto the plurality of layers.
  • T target analyte
  • the metal part may constitute a so-called meta-material, preferably with a periodic nano-material, cf. Busch et al., Physics Reports, 444, (2007), 101-
  • the plurality of layers 11 may be interconnected and curved to form a roll, a so-called nano-roll.
  • the rolling process may be controlled so that the
  • the structure may have a cylindrical symmetry.
  • the metal part of the optical structure is structured or dimensioned in a way so as to obtain negative refractive index (N); N ⁇ 0, at optical frequencies, i.e. at light 30 with frequencies of 10-1500 THz (T for tera; 10 12 ), 1-2000 THz, or 0.5-3000 THz.
  • the structured metal part may be characterized by a negative dielectric constant
  • the form and shape of the nano-roll can be varied by careful preparation and/or 35 tailored growth of the layers to be rolled. It is contemplated that various shapes of the roll may be implemented. Thus, the roll may be shaped as a funnel, a cone, a roll with varying thickness along the length, etc. The roll may also have sharp edges, i.e. having a triangular cross-section, a square-shaped cross-section, a pentagon-shaped cross-section, etc.
  • the present invention also relates to the following examples:
  • porous layer functions as a filter during fluid conduction through the channel.
  • An optical structure comprising a metal part structured in such a way that a negative index of refraction (N) is obtained at optical frequencies, the structure comprising :
  • the layers having a metal part structured in such a way that a negative index of refraction (N) is obtained at optical frequencies, the layers being at least partly transparent to radiation (R_in, R_out),
  • the plurality of layers (11) is optically arranged with respect to a surface (13) of the optical structure so as to facilitate multiple interactions between incoming radiation (R_in) entering the said surface (13) and the plurality of layers and/or the structured metal part, and wherein the plurality of layers (11) is arranged so as to allow direct access for a target analyte (T) into and/or onto the plurality of layers.
  • R_in incoming radiation
  • T target analyte
  • the plurality of layers (11) comprise poly-crystalline Si, single-crystalline Si, SiO 2 , Si 3 N 4 , Al, AI 2 O 37 TiO 2 , SiON-compounds, or glass (phosphor- and/or boron- doped), or doped variations of these materials.

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  • Pathology (AREA)
  • Immunology (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Biophysics (AREA)
  • Optics & Photonics (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

La présente invention a pour objet une structure optique (10, 100, 150) pour spectroscopie exaltée de surface basée sur les plasmons de surface (SP). La structure comprend une pluralité de couches (11) possédant des sites à activité SP, et la pluralité de couches (11) est optiquement disposée de sorte à permettre un accès direct à un analyte cible (T) dans et/ou sur la pluralité de couches. Cette structure optique est avantageuse pour obtenir une sensibilité optique qui puisse être accrue en passant essentiellement d'une structure optique bidimensionnelle (2D), comme cela est connu dans l'art antérieur, à une structure optique tridimensionnelle (3D).
PCT/DK2008/050281 2007-11-29 2008-11-28 Structure optique tridimensionnelle Ceased WO2009068041A1 (fr)

Applications Claiming Priority (4)

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EP07121883 2007-11-29
EP07121883.8 2007-11-29
US99204007P 2007-12-03 2007-12-03
US60/992,040 2007-12-03

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CN102401793A (zh) * 2010-09-14 2012-04-04 精工爱普生株式会社 光器件单元及检测装置
WO2013109280A1 (fr) 2012-01-19 2013-07-25 Hewlett-Packard Development Company, L.P. Dispositif de détection moléculaire
WO2017184120A1 (fr) * 2016-04-19 2017-10-26 Hewlett-Packard Development Company, L.P. Nanostructure plasmonique comprenant un revêtement de passivation sacrificiel

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US20060034729A1 (en) * 2004-05-19 2006-02-16 Vladimir Poponin Optical sensor with layered plasmon structure for enhanced detection of chemical groups by SERS
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US20060197953A1 (en) * 2005-03-07 2006-09-07 3M Innovative Properties Company Thermoplastic film having metallic nanoparticle coating
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US20060034729A1 (en) * 2004-05-19 2006-02-16 Vladimir Poponin Optical sensor with layered plasmon structure for enhanced detection of chemical groups by SERS
US20060164634A1 (en) * 2005-01-27 2006-07-27 Kamins Theodore I Nano-enhanced Raman spectroscopy-active nanostructures including elongated components and methods of making the same
US20060197953A1 (en) * 2005-03-07 2006-09-07 3M Innovative Properties Company Thermoplastic film having metallic nanoparticle coating
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102401793A (zh) * 2010-09-14 2012-04-04 精工爱普生株式会社 光器件单元及检测装置
CN102401793B (zh) * 2010-09-14 2015-07-01 精工爱普生株式会社 光器件单元及检测装置
WO2013109280A1 (fr) 2012-01-19 2013-07-25 Hewlett-Packard Development Company, L.P. Dispositif de détection moléculaire
EP2805153A4 (fr) * 2012-01-19 2015-09-30 Hewlett Packard Development Co Dispositif de détection moléculaire
WO2017184120A1 (fr) * 2016-04-19 2017-10-26 Hewlett-Packard Development Company, L.P. Nanostructure plasmonique comprenant un revêtement de passivation sacrificiel
US10890486B2 (en) 2016-04-19 2021-01-12 Hewlett-Packard Development Company, L.P. Plasmonic nanostructure including sacrificial passivation coating

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